In a network, a router must limit its output rate to be just below the achievable modem upstream rate. Failure to do so will cause delay, or even buffer trail drops (i.e., packet loss), which effects time-critical data, such as video packets. Many throughput measurement techniques have attempted to cure such delay and/or packet loss.
Throughput measurement techniques rely on the ability to send multi-packet bursts and monitor feedback regarding their reception. However, when there are multiple video sources generating upstream traffic, typical QoS policy is to treat all the video streams with the same priority. As a result, packet bursts from each video source will often be interleaved. Thus, estimates of the actual upstream throughput are unreliable.
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